This invention relates generally to the field of classifying machines, and more specifically to guides for supporting articles travelling along the rollers of such machines.
Classifying machines, as defined herein, are machines which use precision made, rotating rollers for the classification, measurement or inspection of articles. The rollers are aligned with their axes in the same plane and with their rolling surfaces facing and spaced apart from each other. They may be oriented in either a parallel or slightly oblique relationship, depending on the task which the machine was designed to perform.
An example of such an apparatus may be found in U.S. Pat. No. 3,874,508 for a CLASSIFYING MACHINE, issued on Apr. 1, 1975, which is incorporated herein by reference. That apparatus contains one roller in fixed relation to a supporting framework, and a second roller, facing the first, which is adjustable relative to it so as to create a gap of desired dimension between the rollers. The rollers are inclined and rotated about their axes during use, so that an article, or workpiece, placed between the rollers at their upper end will be fed along the rollers toward their lower end by a combination of gravity and roller rotation. While the invention is discussed in conjunction with this specific classifying machine, any classifying machine may advantageously employ one or more of the inventive improvements disclosed.
When used for classifying workpieces, the rollers of the above-described classifying machine are usually arranged in an oblique, or "V"-shaped configuration, so that a given workpiece will eventually reach a clearing point and drop between the rollers into a classifying chute or hopper. The machine may also be operated as a travelling "V block" for measuring or otherwise inspecting workpieces whose shapes permit stable seating between the rollers. In this case, the rollers are adjusted to be parallel to each other, and the workpiece being measured or inspected is carried along the length of the rollers. Since the seating of a stable workpiece in the rollers is extremely accurate, an air gauge or similar close tolerance measuring device may be positioned so that workpieces travelling along the rollers are measured when they pass the gauge. Similarly, the workpiece may be inspected, as by a light sensing photocell, to assure that a particular feature of the workpiece (e.g. the centering of a hole in a circular workpiece) is present. As used in this specification, the term "stable" does not refer to the inherent stability of an object, but rather the ability of that object to stably maintain a desired position when it is supported by the rollers of a classifying machine.
A common problem with classifying machines is their inability to maintain certain shapes of objects in a stable orientation while they are being carried along the rollers. In particular, a workpiece in which one dimension is much smaller than its other dimensions cannot easily be stabilized between the rollers unless the smaller dimension is horizontally oriented. For example, a thin, flat washer can be classified according to its depth but not its diameter, because it will not assume a stable position between the rollers if it is horizontally oriented. The washer will generally tilt and fall between the rollers before reaching a point where the spacing between the rollers equals the washer's diameter, resulting in an inaccurate classification of the washer. The range of uses and versatility of such machines would thus be greatly increased if unstable workpieces could be stably supported on the rollers in a desired position, while travelling on the machine.